Chapter 11 - Sleep and biological rhythms Flashcards
Zeitgeber
An external cue for setting biological rhythms
Free-running circadian rhythm
A rhythm that is not synchronized to environmental time cues
Entrainment
The resetting of internal biological clocks to the 24 hour cycle of the earths rotation
Jet lag
Fatigue, irritability and sleepiness resulting from travel across time zones
Suprachiasmatic nucleus (SCN)
An area of the hypothalamus located above the optic chiasm; resposible for maintaining circadian rhythms
Retinohypothalamic pathway
A pathway leading from the retina of the eye to the hypothalamus; provides light information necessary for the maintenance of circadian rhythms
Melanopsin
A photopigment used by non-image-forming (NIF) retinal cells
Melatonin
An indoleamine secreted by the pineal gland that participates in the regulation of circadian rhythms
Cortisol
A hormone released by the adrenal glands that promotes arousal
Seasonal affective disorder (SAD)
A type of depression that results from insufficient amounts of daylight during the winter months
Desynchronous
Having different periods and phases; in EEG, represents relatively low levels of brain activity
Synchronous
Having identical periods and phases; in EEG, represents relatively low levels of brain activity
Beta wave
A brain waveform having 15 to 20 cycles per second, associated with high levels of alertness during wakefulness
Alpha wave
A brain waveform having 9 to 12 cycles per second, associated with less alertness and more relaxation then beta activity during wakefulness
Ultradian cycle
A cycle that occurs several times in a single day
